An anatomic study of Leptinaria unilamellata (Orbigny, 1835) was made emphasizing the genital system, the pallial chamber the radulae and the mandible. The details of these parts characterize better the species and allow more systematic clarity to the group. The importance of the evolutive cycle of the two trematodes, Postharmostomum gallinum (Witenberg, 1923) and Paratanaisia bragai (Santos, 1934) both parasites of domestic birds in Brazil is accentuated.